The present disclosure relates to an edge-light type light source device and a display device.
A display device with a liquid crystal panel, commonly referred to as a thin type such as a liquid crystal television, includes: a substantially rectangular parallelepiped display panel having a surface to display an image in front of it; and a light source device disposed at the back of the display panel and arranged to radiate light toward the display panel.
Examples of the light source device which are employed generally, include a direct light type light source device including: a diffusing plate and a support substrate to support the diffusing plate which are disposed at the back of the display panel; and a light source such as a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED) or the like which is disposed at the back of the diffusing plate, and an edge-light type light source device including: a light guiding plate and a support substrate to support the light guiding plate which are disposed at the back of the display panel; and a light emitting diode positioned opposite to one of the edges of the light guiding plate (reference can be made to, for example, JP 2008-300170 A).
The light source device of edge-light type may include a plurality of light emitting diodes arranged in parallel and opposite to one of the edges of the light guiding plate, and light radiated by the light emitting diodes passes through a light-entering surface and enters the light guiding plate and is diffused by the light guiding plate and emitted from a light-emitting surface of the light guiding plate. It would be advantageous to employ an edge-light type device for the light source device, so that a thickness between the front and back surface of the display device can be reduced, providing a thickness reduction of the display device, when compared with the display device of direct light type, in which a plurality of light sources is arranged in parallel and at the back of the diffusing plate.
Since the light source device of direct-light type includes a plurality of cold cathode fluorescent lamps or light emitting diodes arranged in parallel and opposite to one of the surfaces of the diffusing plate over the entire surface, the heat from the light source, generated when the light source emits light, is conducted to the entire part of the support substrate that is made of metal plate, allowing heat radiation from the entire support substrate.
On the other hand, an edge-light type light source device is often configured to have a reduced space between a light source and a light guiding plate since a broader space between them will reduce a light input efficiency, being unable to provide a required luminance. Therefore, there was a possibility that the light guiding plate could be expanded by the heat from a light source, due to a high linear expansion coefficient of the light guiding plate, and come into contact with the light source, causing breakage of the light source while the heat from the light source, generated when the light source emits light, was conducted to the light guiding plate.